Oil furnace having compartmented air handling systems



Dec. 26, 1967 DE WAYNE THOMAS 3,359,966

OIL FURNACE HAVING COMPARTMENTED AIR HANDLINGSYSTEMS Filed July 18, 1966FIGI INVEN'I 'O R DE AYNE THOMAS ATTORNEY FIGS United States Patent3,359,966 OIL FURNACE HAVING COMPARTMENTED AIR HANDLING SYSTEMS De WayneThomas, Belleville, 111., assignor to International Oil Burner Company,St. Louis, Mo., a corporation of Missouri Filed July 18, 1966, Ser. No.565,766 2 Claims. (Cl. 126110) The present invention relates tooil-burning furnaces for mobile home sand the like, and particularly toimproved air handling provisions therefor.

Combustion of oil is occasionally irregular and accompanied by pulses ofback pressure. Requirements of safety, among others, make it imperativethat the room air circulating system be separated completely from thepath of combustion air.

However, the combustion blower motor requires a cooling flow of air; andcertain auxiliary devices, such as the fuel pump, which are likely tocreate unpleasant odors from time to time, must be available forservicing. These requirements have led to various partial solutions,such as:

(a) Ducting the combustion air directly to the combustion blower,leaving the combustion blower motor, fuel pump and ignition device, andexterior of the burner itself open and near to the air inlet of the roomair circulating system. Oil odors will therefore be communicated to theroom air circulating system; and the suction of the room air circulatingfan will tend to draw combustion gases through any voids which may existat the attachment of the burner to the furnace.

(b) Enclosing the oil pump, combustion blower, motor and burner exteriorin the air passage leading to the combustion air blower. Such a systemis considered unsafe; because to open a door in this air passage toservice these components leads to the possibility that it may be leftopen thereafter; if back-pressure pulses should occur, combustion gaseswould be emitted and drawn into the room air circulating system.

The purposes of the present invention include providing an oil-burningfurnace which may be safely serviced while in operation and yet whichavoids the disadvantages of both of the systems listed above. Furtherpurposes will be apparent from the description which follows.

Generally summarizing the present invention, I provide a furnace cabinethaving an openable sealable compartment in which a combustion blower,motor fuel pump and ignition device are located. An air duct from theexterior of the mobile home penetrates this compartment and supplies allcombustion air adjacent through an air inlet port in the motor casingitself. The air flows internally through the motor easing into the sideof the combustion blower and through ports in the side wheel element ofthe blower wheel. In so flowing, it cools the motor internally. Should aback-pressure pulse occur, it will be communicated harrnlessly to theexterior of the mobile home. Except when the sealed compartment isopened for servicing, there is no air flow past the exterior of the fuelpump, the motor and the other enclosed devices.

A preferred embodiment of the present invention is shown in theaccompanying drawings in which:

FIG. 1 is a schematic side elevation showing an oil burning furnaceembodying the present invention, the separate flows of circulating roomair and of combustion air being shown by the two types of arrowstherein.

FIG. 2 is a perspective view of the removable partition for the scalablecompartment.

FIG. 3 is a front view of the furnace of FIG. 1, the partition of FIG.2, the filter, and the cabinet door being removed.

FIG. 4 is an enlarged fragmentary sectional view taken along line 4-4 ofFIG. 3.

0 wall of the motor casing 60 thus sealed is Ice FIG. 5 is a similarlyenlarged fragmentary view taken along line 55 of FIG. 3.

Referring now to FIGS. 1 and 3, the present furnace comprises arectangular furnace cabinet generally designated 10 having a front door12 including a central louvered air-conducting opening 14. The cabinet10 has a base 11 including a support rim 13 whose bottom flange 15supports the cabinet on the floor 17 of the room in which the furnace 10is installed.

Within the cabinet 10 is a somewhat conventional sheet metal oil-burningfurnace generally designated 16, including a combustion chamber 18having a circular access door provision 20, a heat transfer surface 22which consists essentially of the entire outer and upper surfaces of thecombustion chamber 18, a tubular, upward slanting flue connector portion24, and a scroll-fitted flue casing 26 which connects to the lower endof a conventional flue outlet pipe 28 extending through the roof of themobile home to the exterior atmosphere.

An oil combustion burner, generally designated 30, of the gun type,includes a tubular combustion gun 31 installed in and directedhorizontally into the lower part of the combustion chamber 18. Such oilcombustion burner 30 includes as an auxiliary, a fuel supply device suchas the oil pump 32 shown in FIG. 3, a supply tube 34 therefrom shown inFIG. 5, and an atomizing nozzle 36, within the tubular combustion gun 31and directed into the combustion chamber 18. The furnace also has oilignition devices including an electrical transformer 38 shown in FIGS. 3and 4 connected to a pair of ignition electrodes 40 shown in FIG. 5,which operate in conventional fashion to ignite the atomized oil emittedfrom the nozzle 36.

The room air circulating system commences with the louvered airconducting opening 14 of the cabinet door 12, which serves as a suctioninlet into the cabinet. Air flowing therethrough passes thence through afilter 42 which extends the full cabinet width and is supported at itslower edge on an angle 44 on the outer forward side of an air casing 46which spacedly surrounds the heat transfer surface 22. At the upper partof the air casing 46 is the enclosing scroll 48 of a room aircirculating fan 50 of the conventional squirrel-cage blower type. Airpassing through the filter 42 is drawn into the enclosing scroll 48through a side inlet 52 as shown in FIG. 3. It is driven then downwardbetween the air casing 46 and the heat transfer surface 22, in heattransfer relationship therewith, and thence beneath the combustionchamber 18 outward through a bottom air outlet 54 installed through thefloor 17 into ducts (not shown) which communicate into the room space.The path of flow of the room circulating air is shown in FIG. 1 by theconventional arrows.

Air blown through the combustion air system is shown in FIG. 1 byundulating arrows. The combustion air is drawn from the atmosphereoutside the space to be heated through an inlet air duct 56, shown inFIGS. 1, 3 and 4 as extending through the bottom of the mobile homethrough an opening in the base 11. The duct 56 opens into an invertedrectangular pan-like combustion air conduit 58, beneath the motor casing60 of an electric motor generally designated 62 which powers thecombustion blower hereafter referred to. Downward and inward slopingflanges 64 of the combustion air conduit 58 are sealed against the motorcasing 60 by strips of sealing material 66, as shown in FIG. 4. Theportion of the lower penetrated by a number of slotted air inlet ports68.

The electrical components within the motor casing 60, including itsrotor and stator, are conventional, and are not shown save for the motorshaft which extends through that end of the motor casing 60 which isadjacent to the combustion air blower generally designated 72. At thisend, as shown in FIGS. 4 and 5, the motor shaft 70 is held in a bearing74 supported in the central boss 76 of a ribbed casing end plate 78,provided with arcuate air exit passages 80.

The combustion air blower 72 is best shown in FIG. 5. It includes asheet metal scroll 82 in which a squirrelcage blower wheel 84 is mountedas shown in FIG. 5, in axial alignment with the motor shaft 70. In theembodiment illustrated, a mounting hub 86 is secured to a pressed steelside wheel element 87 having star-shaped spokes 88, the tips of whichsupport an integral circular or ring-like side element 90 in which endsof the impeller blades 92 are held. Spaces between these starshapedspokes 88 serve as air flow ports 96 into the blower wheel 84. Theopposite ends of the impeller blades 92 are held in an open ring-likeside element 90.

The scroll casing 82 has a side element 98 mounted, as by bolts, ontothe ribbed end plate 78 of the motor casing 60. The scroll casing sideelement 98 has a large circular air inlet through which the combustionair is introduced (it must then pass through the blower wheelsstar-shaped spokes 88). Air drawn by the impeller blades 92 passessuccessively through the openings in these three adjacent elements.

The side element 104 of the scroll casing opposite to the side 94-adjacent to the motor 62, is closed. Onto it is mounted the fuel oilpump 32 whose shaft 106 is connected to the motor shaft 70 by a flexiblecoupling 108.

The combustion air system is thus defined not only by the combustionchamber 18, the heat transfer surface 22, the flue connector portion 24,the flue casing 26 and the flue outlet pipe 28, but also by the inletair duct 56 leading into the rectangular combustion air conduit 58, theslotted air inlet ports 68 and the interior of the motor casing 60, itsarcuate air exit passages 80, the air inlet opening 100 in the scrollside elements 98, the air flow ports 96 in the blower wheel side element87, the inside of the scroll casing 82 and the horizontally-projectingtubular combustion gun 31.

Referring to FIGS. 1 and 2, the cabinet 10 is equipped with an openablesealed compartment to enclose the auxiliary fuel supply and ignitiondevices and the outer of the combustion air blower 72 and that part ofthe blower motor casing 60 which is not exposed to the interior of thecombustion air conduit 58. Such sealed compartment is formed by theclose fit of the removable partition generally designated 112, shown inFIGS. 1 and 2. This partition is impervious to air. It has an uppersurface 114 which extends forward from the front side of the air casing46, where it may seal against the angle 44, to near the cabinet door 12;and has a front surface 116 which extends downwardly therefrom at aright angle to the top surface 114 down to the base 11. The edges of theremovable partition 112 are in close, substantially sealed contact withthe furnace cabinet sides and bottom. When the partition 112 is inclosed position as shown in FIG. 1, the air within such compartment issubstantially sealed off from the room air circulating system, guardingthis system from gases, odors and noises. A handle 118 on the uppersurface 114 facilitates removing the partition to open the compartmentfor servicing the apparatus. The combustion air conduit 58 in effectpenetrates such sealed compartment in delivering air through the duct 56in the floor of the mobile home to the slotted air inlet ports 68 in themotor casing 60.

The present construction takes advantage of the fact that of all theelements shown in the lower part of FIG. 3, only the combustion blowermotor 62 requires substantial cooling. Heretofore it has beenconventional to cool such portion of the cabinet as a whole; hence theexterior surface of these mechanical elements have been exposed to aflow of air which (as stated at the beginning of this specification) isopen either to the room air circulating system or to the combustion airsystem. In the present invention, however, all the combustion air to beintroduced into the combustion air blower 72, flows from the exterior ofthe mobile home through the combustion air conduit 58 to the inside ofthe motor casing and thence to the blower scroll 83, thus cooling themotor from the inside. This makes possible the present use of thesubstantially sealed compartment, separate from both the room aircirculating system and the combustion air system.

It will be apparent that oil odors, which are inherent in the region ofthe fuel pump, will not therefore to communicated to the air circulatingsystem. Furthermore, should there be any slight voids in theinstallation of the combustion burner 30 within the combustion chamber18, there is no danger that suction created by the room air circulatingfan 50 will draw combustion gases through such voids into the room aircirculating system. Also, when the partition 112 is removed forservicing, the mechanical units to be served are exposed withoutinterfering with the normal operation of either the room air circulatingsystem or the combustion air system; hence servicing adjustments may bemade safely while the burner is in operation.

Variations in detail from the specific disclosures hereof may be madewithout department from the scope of the present invention. Accordinglythe present invention is not to be construed narrowly, but rather asfully co-extensive with the claims hereof.

I claim:

1. A mobile home oil-burning furnace having improved air-handlingprovisions, comprising a furnace cabinet,

a furnace therein having a heat transfer surface, an oil combustionburner, and auxiliary fuel supply and ignition devices therefor,

further having a room air circulating system including a suction inletinto the cabinet, a circulating fan, air flow casing means to deliverthe air from the inlet through the fan and in heat transfer relationshipwith said heat transfer surface, and an air outlet for such air from thecabinet,

further having a combustion air system including means to ductcombustion gases from the furnace to the exterior of such mobile homeand combustion air supply means including a combustion blower having anair inlet opening,

an electric blower motor having a motor casing including an air exitpassage communicating with the blower air inlet opening, the motorcasing further having an air inlet port, and

an air conduit sealedly secured to said motor casing about its inletport and communicating to the exterior of said cabinet and there havinginlet duct attaching means,

whereby to furnish all combustion air from the exterior of such mobilehome through the motor casing, thereby to cool the said motor,

the cabinet further having an openable sealed compartment which enclosesthe said auxiliary devices and the said combustion air supply means andis penetrated by the said air conduit to the blower motor,

whereby to guard the said suction inlet of the room air circulationsystem from gases, odors and noise when the sealeable compartment isclosed and to permit uninterrupted operation of said combustion airsystem when the compartment is opened for servicing.

2. In an oil burning furnace,

a cabinet having an openable sealable compartment,

and

fuel and combustion air supply apparatus therein, in-

cluding a motor having a shaft extending sidewardly therefrom and amotor casing having an air inlet port and an air outlet spaced therefromand on the side from which the shaft extends,

an air conduit sealedly secured to that part of the motor casing whichincludes said air inlet port, and extending in flow communicationthereto through the said compartment from the exterior of the cabinet,and

a centrifugal combustion blower including a scroll casing having a sideincluding an air inlet opening mounted adjacent to and in flowcommunication with the air outlet of the motor, and having a closed sideopposite thereto,

further having a blower Wheel rotatably mounted in the scroll casing inaxial alignment with and coupled to the said motor shaft,

the blower wheel having blades supported by spacedapart circular sideelements adjacent to the sides of the scroll casing,

that wheel side element adjacent to the air inlet opening in the side ofthe scroll casing having air flow ports therethrough,

whereby all the combustion air is introduced into the combustion blowerfrom the exterior through the air conduit and motor, thereby cooling themotor without air flow in the compartment.

Reierences Cited UNITED STATES PATENTS 3,208,503 9/1965 Biedenbenderl5828 JAMES W. WESTHAVER, Primary Examiner.

1. A MOBILE HOME OIL-BURNING FURNACE HAVING IMPROVED AIR-HANDLINGPROVISIONS, COMPRISING A FURNACE CABINET, A FURNACE THEREIN HAVING AHEAT TRANSFER SURFACE, AN OIL COMBUSTION BURNER, AND AUXILIARY FUELSUPPLY AND IGNITION DEVICES THEREOF, FURTHER HAVING A ROOM AIRCIRCULATING SYSTEM INCLUDING A SUCTION INLET INTO THE CABINET, ACIRCULATING FAN, AIR FLOW CASING MEANS TO DELIVER THE AIR FROM THE INLETTHROUGH THE FAN AND IN HEAT TRANSFER RELATIONSHIP WITH SAID HEATTRANSFER SURFACE, AND AN AIR OUTLET FOR SUCH AIR FROM THE CABINET,FURTHER HAVING A COMBUSTION AIR SYSTEM INCLUDING MEANS TO DUCTCOMBUSTION GASES FROM THE FURNACE TO THE EXTERIOR OF SUCH MOBILE HOMEAND COMBUSTION AIR SUPPLY MEANS INCLUDING A COMBUSTION BLOWER HAVING ANAIR INLET OPENING, AN ELECTRIC BLOWER MOTOR HAVING A MOTOR CASINGINCLUDING AN AIR EXIT PASSAGE COMMUNICATING WITH THE BLOWER AIR INLETOPENING, THE MOTOR FURTHER HAVING AN AIR INLET PORT, AND AN AIR CONDUITSEALEDLY SECURED TO SAID MOTOR CASING ABOUT ITS INLET PORT ANDCOMMUNICATING TO THE EXTERIOR OF SAID CABINET AND THERE HAVING INLETDUCT ATTACHING MEANS,